Perovskite-type composite oxide powder and air electrode for solid oxide fuel cell and solid oxide fuel cell using the same

A perovskite-type composite oxide powder,

• wherein a geometric standard deviation value of a maximum Feret diameter of the perovskite-type composite oxide powder calculated by performing image analysis on an SEM image acquired with a scanning electron microscope is equal to or greater than 1.01 and less than 1.60, and
• when it is assumed that the perovskite-type composite oxide powder is spherical, a ratio (B/A) of an area value B directly calculated by the image analysis to an area value A calculated from the maximum Feret diameter is equal to or greater than 0.7 and less than 1.0, and
• the perovskite-type composite oxide powder has a composition represented by a general formula ABO3-δ (where an A element includes lanthanum as an essential component, and optionally includes one or both of strontium and calcium, a B element is at least one selected from manganese, cobalt, nickel and iron and δ represents an amount of loss of oxygen).